Computer was turned off. Next day nothing. No fans, no lights. Nothing working. I tested the power supply. OK. Can a power supply be bad, but test ok. Most computer I have this problem with is a bad power supply. I'm looking at MB next.

I tested the power supply. OK. Can a power supply be bad, but test ok.

Depends on how it was tested. The correct way to fully test a power supply is while under a realistic load with some form of waveform analyzer (oscilloscope or power analyzer) by a trained technician. A volt-meter is not good enough. Short of that, you swap in a known good, properly sized, power supply. I also keep a FrozenCPU Ultimate PSU Tester for PSU testing in my tool bag when I am away from home. It is not as good as a qualified technician testing the PSU under a "true" (realistic) load with an oscilloscope or power analyzer, but close.

I'm looking at MB next.

Only if sure it is not the power supply. How was it tested?

I have a power supply tester. The tester showed the power supply ok. With the tester the case fans work ok. I know with computers anything can happen & will sooner or later. I used my last power supply the other day. I try to keep one on hand.

The testers are not good enough. They can still show a supply as good, when it is not. They do not show the ripple value, which if too high, can cause stability issues. And they do not present a realistic load.

Although your symptoms can be caused by other things - bad RAM, bad CPU, bad motherboard, it points to power. And you need to verify that before preceeding.

I think power supply is the problem. Thanks for your help. I try to keep a power supply on hand. Will get one & see. Thanks

Good luck and keep us posted.

For the time being the new power supply is up & running. Now I have one of the computer from the church. I have a feeling power supply is bad. Something new with each computer that you try to fix. Thanks for your help.

Something new with each computer that you try to fix.

That's the fun part.

The new power supply for the computer from the church has it up & working. Two difference computer problems, but power supply fixed computers.

Well you gotta feed electronics good food! Thanks for the followup.